The present invention relates to a method and to apparatus for regulating the temperature of a motor vehicle cabin.
The state of the art, and in particular FR-2 697 210 discloses a method of regulating the temperature of a motor vehicle cabin, which method is of the type in which heat is delivered to the cabin from a hot source of a heat pump having a compressor circuit for a refrigerant fluid that takes heat from a cold source and transfers at least part of that heat to the hot source.
The compression circuit generally comprises an evaporator in heat exchange with the cold source, and a condenser in heat exchange with the hot source, these elements being interconnected by a compressor and an expander. The refrigerant vaporizes in the evaporator, thereby taking heat from the cold source. The compressor draws in the vaporized refrigerant and delivers it into the condenser cooled by heat exchange with the hot source, and the refrigerant condenses in the condenser. The expander allows the refrigerant in the liquid state to pass to the evaporator by lowering its pressure.
A heat pump can be used either to heat a space or a part, or else to cool said space or said part.
In FR-2 697 210, the cold source has firstly a first refrigerant/coolant heat exchanger thermally coupling the refrigerant circuit which constitutes a main circuit with a first secondary coolant circuit, and secondly the hot source has a second refrigerant/coolant heat exchanger thermally coupling the main refrigerant circuit to a second secondary coolant circuit.
The secondary circuits are capable of being selectively connected via appropriate valves to an outside heat exchanger placed in the vehicle engine compartment, and to an inside heat exchanger placed in the vehicle cabin. By acting on the valves, the heat pump can be used either to refrigerate the vehicle cabin (in this first case, the hot source is the outside heat exchanger and the cold source is the inside heat exchanger), or else to heat the cabin (in this second case the hot source is the inside heat exchanger and the cold source is the outside heat exchanger).
It should be observed that in the second case, the performance of the heat pump is limited by the temperature of the outside air. In the cold season, air temperature limits the efficiency of the heat pump while it is being used for the purposes of heating the cabin. Furthermore, frosting of the cold source in the cold season can harm the operating performance of the heat pump.
An object of the invention is to optimize the performance of temperature regulation apparatus using a heat pump, in particular when it is used for heating the cabin of a motor vehicle.
To this end, the invention provides a method of regulating the temperature of a motor vehicle cabin of the above-specified type, characterized in that heat coming from a flow of recycled cabin air is taken from the cold source.
The invention also provides apparatus for implementing the above-defined method, the apparatus being characterized in that the cold source comprises a first refrigerant/coolant heat exchanger thermally coupling the main refrigerant circuit to a first secondary coolant circuit capable of being selectively connected to an xe2x80x9coutsidexe2x80x9d heat exchanger and to a xe2x80x9ccoldxe2x80x9d heat exchanger, and in that the hot source comprises a second refrigerant/coolant heat exchanger thermally coupling the main refrigerant circuit to a second secondary coolant circuit capable of being selectively connected to the outside heat exchanger and to a xe2x80x9chotxe2x80x9d heat exchanger.
According to other characteristics of this apparatus:
the cold and hot heat exchangers are coolant/air heat exchangers;
the cold and hot heat exchangers are arranged in an air conditioning unit preferably disposed in the cabin, the unit defining air flow circuits passing through the cold and hot heat exchangers;
the air flow circuits comprise a xe2x80x9crecycledxe2x80x9d air inlet for air recycled from the cabin, an xe2x80x9coutsidexe2x80x9d outlet for delivering air to the outside of the vehicle, first connection means for connecting the recycled air inlet to the upstream end of the cold heat exchanger, and second connection means for connecting the downstream end of said cold heat exchanger to the outside outlet;
the second connection means comprise air distribution means for distributing air to the upstream end of the hot heat exchanger and to the outside outlet;
the air flow circuits comprise an xe2x80x9coutsidexe2x80x9d air inlet for admitting air from outside the vehicle, a xe2x80x9ccabinxe2x80x9d air outlet for delivering air to the cabin, third connection means for connecting the outside air inlet to the upstream end of the hot heat exchanger, and fourth connection means for connecting the downstream end of the hot heat exchanger to the cabin outlet;
the third connection means comprise air distribution means for distributing air to the upstream end of the hot heat exchanger and to the upstream of the cold heat exchanger;
the air conditioning unit comprises means for driving air, said means being arranged upstream or downstream from the cold heat exchanger; and
the air conditioning unit comprises means for driving air, said means being arranged upstream or downstream from the hot heat exchanger.